Attorney General William P. Barr on Tuesday signaled that the Justice Department plans to step up its scrutiny of Silicon Valley, exploring new legal tools to probe companies for their privacy abuses and the way they police content online.

Barr didn’t mention companies such as Amazon, Facebook and Google by name, but his speech — delivered to state law enforcement officials in Washington — amounted to the latest high-profile warning for Silicon Valley at a moment when major tech companies already are under investigation for their business practices. (Amazon founder and chief executive Jeff Bezos owns The Washington Post.)

The attorney general also said the Justice Department is taking a closer look at decades-old laws that spare tech companies from being held liable for content posted by their users. Those rules, known as Section 230, are considered some of the most prized legal protections in Silicon Valley, sparing them from some lawsuits and other punishments.

“We’ve heard widespread concerns from consumers, businesses, [and] entrepreneurs, including about stagnated innovation, high prices, lack of choice, privacy, transparency and public safety, and in response, DOJ initiated a review into market-leading online platforms,” Barr said.

The attorney general later added: “We are thinking critically about how DOJ and our state partners can address other topics related to online platforms such as privacy, transparency, consumer fraud, child exploitation or public safety."

In July, the Justice Department announced a wide-ranging review of “market-leading online platforms,” citing competition concerns in “search, social media, and some retail services online.” Since then, the agency’s antitrust division has embarked on more focused antitrust investigations into Facebook and Google, amounting to a major new legal headache for an industry that long dodged such regulatory scrutiny in Washington.

Opening his speech, Barr joked that Democrats and Republicans had found rare alignment in their concerns about big tech. He said the same about state attorneys general, nearly all of whom have banded together across the country to open their own probes into Facebook and Google to see if they have harmed competition or consumers.

“I think this demonstrates the importance of these issues to Americans across the country regardless of location or political persuasion,” Barr said.

The attorney general stressed the department’s review of major technology companies would encompass far more than traditional antitrust concerns, exploring the extent to which their massive data stores offer them a competitive advantage and even their approach to political posts, photos and videos online.

Barr pointed to unnamed critics in raising concerns that social media sites may stifle some “third-party speech, including political speech, selectively and with immunity.” His concerns appear to echo those of President Trump, who has accused Facebook, Google and other companies of censoring conservatives online. Trump has not provided systemic evidence of such political bias, and the three major social media companies have denied it.

In response, Barr said the Justice Department is exploring recommending possible changes to Section 230, pointing to critics who say the rules have been “expanded far beyond what Congress originally intended." Amazon, Facebook, Google and their top Washington advocates have fought fiercely for years to protect their liability shield, pointing to the fact that it actually gives them the legal basis for moderating their sites in the first place.

Barr, however, said the department is “thinking critically on the issue.”